| ??? 05/22/07 17:59 Modified: 05/22/07 18:16 Read: times |
#139632 - tricks & tricks Responding to: ???'s previous message |
There is nothing wrong in sampling a repeated signal - I remember a scope my professor was using during my PhD study, he made some laser chips and this one was able to sample and display on a persistent screen (fully analog) nice waveform of the laser output, being modulated with some ns pulses - all made in USSR somewhere deep in the 70s, too... :-) I was SHOCKED.
The bad thing is, if this figure is the BIGGEST NUMBER written on the box, with the sub-mm explanation text far far below... --- But it's not only the superfast ADC which makes a fast DSO. A measurement is only as good as the weakest chain of it. A bad connector or cable can spoil everything. Also, there are tricks how to make fast sampling yet use relatively slow ADCs; mostly based on a fast set of sample-and-hold circuits and a well-thought clock and signal distribution (propagation) across them. Massive parallelism is one of those, simply having an array of relatively slow ADCs, all connected to one S/H output. Or, a CCD-like scheme can be employed, the S/H being then basically analog memories containing the samples. This all allows to achieve GSps sampling rates on silicon, without need to resort to exotic III-V semiconductor technologies. But the scheme I liked the most was a CRT-like screen, where the input was applied to the electron beam modulation, and the acquired waveform was "stored" as a single sweep into the slowly decaying light output of the CRT phosphor (luminophore), being read out by a conventional CCD array... JW PS. Rob, don't you happen to be around Tilburg by the last weekend of August? |
| Topic | Author | Date |
| [OT] DSO- How it's made ? | 01/01/70 00:00 | |
| look at ADC spec's. | 01/01/70 00:00 | |
| in other words, | 01/01/70 00:00 | |
| Not quite | 01/01/70 00:00 | |
| tricks & tricks | 01/01/70 00:00 | |
| Analog memories... | 01/01/70 00:00 | |
| that's what the analog 'scope does! | 01/01/70 00:00 | |
| Some interesting reading from Maxim | 01/01/70 00:00 | |
| I have no doubt you can | 01/01/70 00:00 | |
| use for what | 01/01/70 00:00 | |
| Expansion slot test equipment | 01/01/70 00:00 | |
| there is now a plethora of such with USB | 01/01/70 00:00 | |
| crappy GUI | 01/01/70 00:00 | |
| I prefer the "feel" of manually controlled gear | 01/01/70 00:00 | |
| Can't be done, or just hasn't been done? | 01/01/70 00:00 | |
| there's no reason it couldn't | 01/01/70 00:00 | |
| The PeeCee would get in the way | 01/01/70 00:00 | |
| not only... | 01/01/70 00:00 | |
| a few buttons, dials, and knobs, but not enough | 01/01/70 00:00 | |
Critics and suggestions invited - 1GHz sampler | 01/01/70 00:00 |